This invention relates to a thermoplastic engineering resin composition comprising a blend of a polyindane resin and an engineering thermoplastic such as polyphenylene ethers, polysulfones, and polycarbonates. These blends provide improved processability with good physical properties including impact strength and high heat distortion temperature. The polyindanes of this invention also provide similar benefits to the processing of thermoplastic block copolymers.
Engineering thermoplastics, such as polyphenylene ethers, polysulfones, and polycarbonates, have many desirable properties including outstanding electrical and mechanical properties, high heat distortion temperatures and self extinguishing properties. These high molecular weight polymers are useful for many commercial applications requiring high temperature resistance dimensional stability and electrical properties. However, for many uses the high melt viscosities and softening points are a disadvantage. For example, polyphenylene ether has a high glass transition temperature (211.degree. C.), and the resin has a high melting point (262.degree.-267.degree. C.) and a high melt viscosity. Molded articles can be formed by melt processing techniques, but again, the high temperatures required are undesirable. Above 250.degree. C. in the presence of oxygen, polyphenylene ether is rapidly degraded with the formation of gel and colored by-products. The resin is brittle and has low impact resistance.
Accordingly, efforts have been made to improve the melt flow by reducing the melt viscosity of the resins and their alloys. In general, these efforts have involved the use of a plasticizer, small amounts of low molecular weight compounds, aromatic and branched polyesters, polycarbonates, etc.
In U.S. Pat. No. 3,383,435 polystyrene is blended with polyphenylene ether to obtain improved processability. These blends provided many improved properties over either the styrene resin or the polyphenylene ether. However, they exhibit lower heat distortion temperatures compared to the polyphenylene ether resin.
U.S. Pat. No. 4,123,410 discloses a blend of polyphenylene ether and a plasticizer, such as a triphenyl phosphate, poly(1,4-butylene terephthalate) or a branched copolyester, and an impact modifying A-B-A copolymer of styrene. The heat distortion temperature was significantly reduced in the data shown.
U.S. Pat. No. 4,167,507 discloses compositions consisting of a polyphenylene ether and a hydrogenated block copolymer of the ABA type, where A designates a polymerized mono-alkenyl aromatic hydrocarbon block such as polystyrene and B designates a polymeric diene block. These blends had high impact strength, but heat distortion temperatures were significantly reduced when compared to polyphenylene ether resins.
In U.S. Pat. No. 4,189,411, is disclosed a mixture of a polyphenylene ether, a styrene resin and a resinous material having a softening point above the heat distortion temperature of the final composition. The resulting composition had significantly lower heat distortion temperatures than polyphenylene ether.
U.S. Pat. No. 4,385,146 discloses the use of tribenzylphosphine oxide to lower the viscosity of a polyphenylene ether resin-polystyrene blend.
U.S. Pat. No. 4,491,649 discloses polyphenylene ether resins modified with an ABA block copolymer or a polyolefin and an aromatic polycarbonate. These blends exhibit improved processability, useful properties and less reduction in heat distortion temperatures than prior art blends.
U.S. Pat. No. 4,530,952 discloses the use of diamides to improve the flowability of polyphenylene ether resins with minimal effect on heat resistance. In U.S. Pat. No. 4,684,684 these diamides were used to modify other thermoplastic resins such as polystyrenes, polycarbonates, polynorbornenes, polyarylates and polysulfones. A broader disclosure of amides as fluidity improving agents is disclosed in U.S. Pat. No. 4,663,375.
U.S. Pat. No. 4,544,703 discloses thermoplastic compositions comprising polyphenylene ether and polyalkenyl aromatic resin (e.g. styrene, chlorostyrene, alpha-methylstyrene, vinyl xylene, divinyl benzene and vinyl naphthalene).
U.S. Pat. No. 4,563,500 discloses a polyphenylene ether resin combined with a styrene resin and with a combination of a block copolymer of the unsaturated type and a block copolymer of the saturated type. This combination provided improved melt flow, lowered cost and improved impact strength. However, including a styrenic resin and/or plasticizer, for attaining good mold flowability, substantially reduces the HDT value of such blends and thereby limits their upper end use temperatures.
U.S. Pat. No. 4,579,901 discloses compositions consisting of a combination of a polyphenylene ether resin or a polyphenylene ether resin modified with an alkenyl aromatic resin and a low viscosity polyester based plasticizing agent. Among the polyester plasticizers that are employed are those obtained as a reaction product of adipic acid and phthalic anhydride.
Although incorporation of melt flow modifiers as in the above referenced patents improves processability by reducing the melt viscosity, generally it leads to significant reductions in the heat deflection temperature and other desirable properties. On many occasions, such additives also cause incompatibility problems.
Another thermoplastic resin that would be desirable to process at lower temperatures is polyetherether ketone (PEEK). PEEK is a semi-crystalline engineering thermoplastic polymer having a high glass transition temperature (160.degree. C.). It exhibits excellent mechanical and electrical properties, high heat distortion temperature and finds use in many composite applications. However, it has a high melting point, about 340.degree. C. Thus, it has only been possible to melt process PEEK at temperatures above 350.degree. C., typically at approximately 380.degree. C. Heating at high temperatures, particularly if prolonged, as experienced during molding, is known to disturb PEEK's crystallization behavior which ultimately affects its physical properties. PEEK is also used for carbon fiber composite applications. Due to its high melt viscosity, the coating of PEEK onto carbon fiber is extremely difficult. High pressure must be exerted to improve PEEK'S wetting onto carbon fiber. Fiber spinning of PEEK at high temperatures, such as at 380.degree. C. has also been very difficult. At such temperatures, the material tends to gel, resulting in screen pack plugging or frequent fiber breakage during take up. It is thus desirable that PEEK be melt processed at lower temperatures. Similar difficulties have been seen in the addition of additives to PEEK as in other thermoplastic resins previously described.
It is therefore an object of the current invention to improve the melt processability of engineering thermoplastics such as polyphenylene ethers, polysulfones, aromatic polycarbonates, polyether ether ketones, polyarylates, polyphenylene sulfides, polyimides, polyamides and polyarylether ketones and their alloys/blends. Another object of the invention is to prepare compositions without causing significant incompatibility problems in polymer performance. Yet another object of the invention is to prepare such compositions without lowering the thermal resistance, i.e., without lowering the glass transition (T.sub.g) and heat distortion temperatures (HDT) of the thermoplastic.